Watercraft, including personal watercraft, are often powered by an internal combustion engine having an output shaft arranged to drive a water propulsion device. The engines which are used to power personal watercraft are most often of the two-cycle variety. These engines generate a large amount of hydrocarbon exhaust.
Unfortunately, when this exhaust is exhausted from the watercraft, it may react with the water in which the watercraft is located and form acids and other undesirable compounds, and may also be released from the water into the atmosphere.
The use of catalytic converters is known for use in oxidizing carbon monoxide and hydrocarbons into carbon dioxide and water, and reducing oxides of nitrogen into nitrogen. While the use of a catalytic converter is desirable with these types of engines, several problems generally arise with their use with engines powering personal watercraft.
First, the catalyst is typically positioned in an exhaust pipe leading from the engine. In personal watercraft, this exhaust pipe leads through a chamber in the hull of the craft to an outlet near the stern. This arrangement causes the exhaust pipe to be susceptible to vibration which may cause damage to the honeycomb structure of the catalyst.
In addition, in personal watercraft the amount of space in which the engine may be positioned is limited so as to maintain the craft small in dimension and with a low center of gravity. The catalyst must also not be place too near the engine or it will overheat, and must not be place to far from the engine or it may be susceptible to the condensation of liquids and the entry of water backwardly through the exhaust system.
An exhaust control for an engine of the type utilized to power a watercraft which is includes a catalyst and which overcomes the above-stated problems, is desired.